Always thinking about a Merc 350mag SBC performance bump / build

[wowchad]

So I have a 350mag in our Nordic 22Evo and I'm thinking about adding some engine mods to take advantage of my CMI's
Blower is 6k, hairdryer is about $4500, but what about just heads and cam?
Looking to keep the reliability!

 

[hallett21]

I'm wondering what you could sell your motor for? Take the 6k plus whatever you get and put it towards a bigger power plant. How many mph are you trying to get out of your upgrade?

 

[wowchad]

I'm invested in keeping the 350 and know street guys build the heck out of them. They are cheap, good fuel economy and light which I like.

I'm just looking to open the flow and tickle 400'ish HP & I'd be happy.

I know HP / reliable & cheap don't belong on the same page as one another, but can't a guy do quality iron heads, cam and intake for well under $4000??

Who's the go-to for SBC Marine expertise? I know there are plenty of these engines out there.

Back in the day AZ Speed was a big player and Tyler something in MI...I've been out of touch for a bit thou.
Chad

 

[obnoxious001]

Certainly you can do heads and a cam for under $4K, but you do need to consider what rpm range you will be using the engine in. It could make more sense to put a stroker kit in to increase cubic inches, possibly leaving the stock heads (I have no idea what is stock on that engine), and an improved camshaft. How old is your current engine?

 

[Trash]

I did an EFI small block. PM for details if desired.

Bottom line is stroker is recommended. In the 'food for thought' department you can pick up a Dart SHP (small block) 427 short block assembly for about $5k. That motor will make some robust power in a small package.

Heads and cam along with the stroker can get 400+ fairly easy. Price depends on parts, machining and assembly.

 

[djunkie]

What Outdrive do you have?

 

[Runs2rch]

This is where I am at. We have a pair of carbed 350 Mags.

Thinking Profiler 185 heads, Lunati 20080720 cam, set of rr's, Eddy rpm air gap, and Quick Fuel 650 carb. Already have EMI exhaust.

Thinking this combo will turn 5200-5400 making 360-370hp.

Trash and Junkie what do you think?

 

[Trash]

This is where I am at. We have a pair of carbed 350 Mags.

Thinking Profiler 185 heads, Lunati 20080720 cam, set of rr's, Eddy rpm air gap, and Quick Fuel 650 carb. Already have EMI exhaust.

Thinking this combo will turn 5200-5400 making 360-370hp.

Trash and Junkie what do you think?

I'm not familiar with the Profiler heads. AFR 195s are probably ideal.

The Lunati is good, but you could go bigger. You might need a little more cam for that HP or a stroker to help reach the 360 hp mark.

Are you going stroker or just an .030" motor?

 

[Tinkerer]

There is a ton of stuff out there for the SBC. 400HP would be easy to build. Just remember boats don't need HP they need torque and the easiest way to make torque is cubic inches. I ran into this problem with my 509's they didn't make enough torque. I built a 598. That should solve the problem.
I would stroke what you have or better yet buy a short block, add AFR heads, single plane intake manifold and a hydraulic roller cam. I was producing over 500HP from a FORD 302 many years ago. But that engine had to be taken apart every winter. To say it was rather radical was an understatement.

 

[Runs2rch]

I'm not familiar with the Profiler heads. AFR 195s are probably ideal.

The Lunati is good, but you could go bigger. You might need a little more cam for that HP or a stroker to help reach the 360 hp mark.

Are you going stroker or just an .030" motor?

The 195's seem like they would be too large. Check out profiler heads. The flow numbers are really solid. 30 over 9.5 compression. You run a Crower grind right?

 

[NicPaus]

Is it the 350 mag 300hp with bravo 3 outdrive? Another member went this route last year. Much better to just buy a take out 496 HO for $6 or 7K ans sell the old.

 

[Trash]

The 195's seem like they would be too large. Check out profiler heads. The flow numbers are really solid. 30 over 9.5 compression. You run a Crower grind right?

I don't think they'd (AFR 195s) be too large, but if you're happy with the Profiler I say go for it.

I run Crower valve train.

 

[wowchad]

What Outdrive do you have?

It's a Bravo so I'm good there.

Several years ago I had a 20' Baja with a 454 and the Alpha drive, plus it had a Land & Sea Stern Jack on it. Fast little boat, but I always worried about that drive on there.

 

[wowchad]

I did an EFI small block. PM for details if desired.

Bottom line is stroker is recommended. In the 'food for thought' department you can pick up a Dart SHP (small block) 427 short block assembly for about $5k. That motor will make some robust power in a small package.

Heads and cam along with the stroker can get 400+ fairly easy. Price depends on parts, machining and assembly.

I know it's best to swap in a BBC, but I'm sticking with a SBC build. One thing I need to do is figure out exactly what I have though, it's a 2010 boat...I don't know how to I.D. the ECM.

I've actually been contacting a few marine engine builders and it sounds like a short block is my best bet.
It doesn't have to go 80mph and like I said, around 400HP with an increase in torque is what I'm looking for, nothing radical, I WANT IT TO BE SUPER RELIABLE!

I'll admit I'm pretty green and will be paying someone to put the engine together. I'll yank the engine and re-install, but I'm not looking for a lesson in cams, head flow etc.
I can't believe someone doesn't have a package already put together to do this. There are so many of these engines out there!
Trash I'll send you a PM, thanks!

 

[AzGeo]

I know it's best to swap in a BBC, but I'm sticking with a SBC build. One thing I need to do is figure out exactly what I have though, it's a 2010 boat...I don't know how to I.D. the ECM.

I've actually been contacting a few marine engine builders and it sounds like a short block is my best bet.
It doesn't have to go 80mph and like I said, around 400HP with an increase in torque is what I'm looking for, nothing radical, I WANT IT TO BE SUPER RELIABLE!

I'll admit I'm pretty green and will be paying someone to put the engine together. I'll yank the engine and re-install, but I'm not looking for a lesson in cams, head flow etc.
I can't believe someone doesn't have a package already put together to do this. There are so many of these engines out there!
Trash I'll send you a PM, thanks!

BUT, building and testing a number of motor sizes and packages 'on your own dime', is not affordable .

I had 'packages for smaller motors' in my shop back in the 1980's . Once we got drives that could handle more power, customers moved into big blocks and the demand for 'small block performance' fell off the charts .

Any performance engine that runs under 5252 RPMs is known as a 'torque motor build', and with the ECM controlling your top RPMs you need a motor that creates it's max power between 1500 and 5000 RPMs .

Cubic inches is the quickest way to make 'more torque at lower RPMs', so the shops are steering you in the right direction .

I must say that since you will be using the factory EFI intake, I see no need for an open exhaust system, high performance exhaust manifolds, a cam with longer exhaust duration, nor aftermarket performance cylinder heads .

The 'brain' of a motor is it's cam and the timing of the valve events . This is what makes the torque here Grasshopper, not all the 'add on BS parts' .

All the parts must work together, with a strong pull from idle to 5000 RPMs, pretty simple with a 'flat tappet cam', more meaty with a 'hydraulic roller cam' .

 

[wowchad]

...I must say that since you will be using the factory EFI intake, I see no need for an open exhaust system, high performance exhaust manifolds, a cam with longer exhaust duration, nor aftermarket performance cylinder heads .

The 'brain' of a motor is it's cam and the timing of the valve events . This is what makes the torque here Grasshopper, not all the 'add on BS parts' .

All the parts must work together, with a strong pull from idle to 5000 RPMs, pretty simple with a 'flat tappet cam', more meaty with a 'hydraulic roller cam' .

Sounds like I need to find a different intake then, but I would like to keep the thing EFI.
Since I already have the CMI's I thought this would be an easy head/cam combo and done...it's quickly turning into a whole different animal!

What was so special about the old Merc Racing Scorpion engine? Couldn't I use a similar intake? Or I see Merc is now offering higher power rated SBC engines these days, what about using one of those intakes??

 

[Trash]

Sounds like I need to find a different intake then, but I would like to keep the thing EFI.
Since I already have the CMI's I thought this would be an easy head/cam combo and done...it's quickly turning into a whole different animal!

What was so special about the old Merc Racing Scorpion engine? Couldn't I use a similar intake? Or I see Merc is now offering higher power rated SBC engines these days, what about using one of those intakes??

If you can find a Scorpion intake that would be cool (it's basically what I have) but they are rare as hens teeth and would likely cost a fortune. I would not be too quick to dismiss your current intake. A good combo of heads, cam and stroker will get you what you need. You will need to spin the motor a little faster so the rev limiter value in the MEFI will need to be changed.

 

[AzGeo]

Sounds like I need to find a different intake then, but I would like to keep the thing EFI.
Since I already have the CMI's I thought this would be an easy head/cam combo and done...it's quickly turning into a whole different animal!

What was so special about the old Merc Racing Scorpion engine? Couldn't I use a similar intake? Or I see Merc is now offering higher power rated SBC engines these days, what about using one of those intakes??

If you want to keep throwing money at it, sure you can do what you like .

Going into the programming will not be cheap, easy, or done in 4 or 5 tries . (if the motor does not quit first)

I try to stay away from going into the ECM for any reason . It would be cheaper and quicker to just go with a 'Mega Squirt' ECM and tune it all yourself, IF you need so much power that you need to raise the Rev Limiter .

The deal is that normal brand name marine motors are made 'weak' so they last thru out the warranty period .

Just doing some 'minor improvements' will wake up all black motors and most blue ones too .

I remember doing a Capri 20.5' Bayliner, 305 Merc 2 bbl Alpha, 600 Holley, dual plane intake, 485/224, 485/224 on 112 centers, in @ 107 (American Cams) . New good springs, carb work, 2 degrees more spark advance . Thru the prop stock exhaust . Originally 4700 RPMs with a 19 pitch, after work, 5000 RPMs with a 21 pitch, and much quicker to speed .

For EFI, a 22' Daytona, 454 MPI Bravo I, with a 24 pitch Bravo 4 blade . He destroyed the crank, rods and main saddles . Repaired the block, installed an Eagle 4.25" crank with longer rods, so it had to go .060" over, which made it 496" . Used a Crane flat tappet cam equal to the Merc '525HP' grind (in @ 110), with new springs . Used the 'vapor separator', but welded a fitting to it, and ran a 700HP fuel pump and adjustable regulator . Ran a colder 140 F thermostat, with a 5K ohms resistor to fool the stock ECM . Had injectors 'cleaned and flow tested', 85% duty cycle was well over 600 HP of fuel volume, so kept them .
Boat runs the river on the rev limiter with a 28 pitch 4 blade, and 4900 with a 27/3 blade at Powell .

These are two of the 'mild improvements' I can remember doing over the years .

You may need more, but consult with the person who actually does the 'ECM changes' before you go in that direction . Get his estimate in writing . Merc/Motorola is based on GM tech and it's 'cross connected', within the programming .

 

[Trash]

Going into the programming will not be cheap, easy, or done in 4 or 5 tries . (if the motor does not quit first)

I try to stay away from going into the ECM for any reason . It would be cheaper and quicker to just go with a 'Mega Squirt' ECM and tune it all yourself, IF you need so much power that you need to raise the Rev Limiter .

You may need more, but consult with the person who actually does the 'ECM changes' before you go in that direction . Get his estimate in writing . Merc/Motorola is based on GM tech and it's 'cross connected', within the programming .

So how much does Mega Squirt system cost?

What about tuning his existing MEFI himself?

What are you talking about when referencing Merc/Motorola and cross connected within the programming?